Use of Diodes in Filters??

[Rob Hukin]

>> One trick one may play with the diode is to stack multiple of thems
>> such that you migth get better signal to noise ratio (less noise that
>> is). An extreme case of this is found in the EMS Hi-Fli where the
>> phaser section contains a stack of 20 diodes per AP filter, there is a
>> total of 12 in the Hi-Fli which results in just 240 diodes for the
>> core phase block itself.

Maybe i'm missing something here, but isn't there a relationship between
the number of diodes in the ladder and filter order? So, in the EMS filter,
diodes D3, 4, 5, 10, 11 and 12 maybe to do with matching/better SNR, but
the rest and required to get a 4-th order response?

rob.